Research Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease Marc Miravitlles*1, Alicia Marín2, Eduard Monsó3, Sara Vilà1, Cristian de la R
Trang 1Open Access
R E S E A R C H
any medium, provided the original work is properly cited.
Research
Colour of sputum is a marker for bacterial
colonisation in chronic obstructive pulmonary
disease
Marc Miravitlles*1, Alicia Marín2, Eduard Monsó3, Sara Vilà1, Cristian de la Roza4, Ramona Hervás3, Cristina Esquinas1, Marian García3, Laura Millares3, Josep Morera3 and Antoni Torres5
Abstract
Background: Bacterial colonisation in chronic obstructive pulmonary disease (COPD) contributes to airway
inflammation and modulates exacerbations We assessed risk factors for bacterial colonisation in COPD
Methods: Patients with stable COPD consecutively recruited over 1 year gave consent to provide a sputum sample for
microbiologic analysis Bronchial colonisation by potentially pathogenic microorganisms (PPMs) was defined as the isolation of PPMs at concentrations of ≥102 colony-forming units (CFU)/mL on quantitative bacterial culture Colonised patients were divided into high (>105 CFU/mL) or low (<105 CFU/mL) bacterial load
[% predicted] 46.4%) were evaluated Bacterial colonisation was demonstrated in 58 (48.7%) patients Patients with and without bacterial colonisation showed significant differences in smoking history, cough, dyspnoea, COPD
exacerbations and hospitalisations in the previous year, and sputum colour Thirty-six patients (62% of those colonised) had a high bacterial load More than 80% of the sputum samples with a dark yellow or greenish colour yielded PPMs in
culture In contrast, only 5.9% of white and 44.7% of light yellow sputum samples were positive (P < 0.001) Multivariate analysis showed an increased degree of dyspnoea (odds ratio [OR] = 2.63, 95% confidence interval [CI] 1.53-5.09, P = 0.004) and a darker sputum colour (OR = 4.11, 95% CI 2.30-7.29, P < 0.001) as factors associated with the presence of
PPMs in sputum
Conclusions: Almost half of our population of ambulatory moderate to very severe COPD patients were colonised
with PPMs Patients colonised present more severe dyspnoea, and a darker colour of sputum allows identification of individuals more likely to be colonised
Background
Exacerbations are the main cost driver in chronic
obstructive pulmonary disease (COPD), have a negative
impact on the clinical course of the patients and are
asso-ciated with increased mortality [1-3] Around 70% of
exacerbations are infectious in nature, either bacterial,
viral or mixed [4-7] It has been shown that airway
bacte-rial load in the stable state contributes to airway
inflam-mation and modulates the character and frequency of
exacerbations [8,9] There is also evidence that bronchial
colonisation influences the decline in lung function over time [10] Different studies in which respiratory samples were obtained by the protected specimen brush (PSB) technique have shown a high prevalence of bronchial col-onisation in COPD patients [5,11,12] However, the prac-tice of bronchoscopy to assess bronchial colonisation in routine clinical practice is not feasible and data that sup-port the use of sputum samples to identify patients colo-nised by potentially pathogenic microorganisms (PPMs) are required
Consequently, a cross-sectional study was designed to assess the frequency of bronchial bacterial colonisation using sputum samples and to identify risk factors for col-onisation in stable ambulatory patients with COPD The
* Correspondence: marcm@separ.es
1 Fundació Clínic Institut D'Investigacions Biomèdiques August Pi i Sunyer
(IDIBAPS) Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
Full list of author information is available at the end of the article
Trang 2clinical characteristics of patients colonised and
non-col-onised with PPMs were compared as were those of
patients with low and high bacterial loads in sputum
sam-ples
Methods
A cross-sectional study was carried out to assess clinical
characteristics associated with bronchial colonisation in
stable ambulatory COPD patients These patients were
visited at the outpatient respiratory clinics of two
acute-care tertiary hospitals in Barcelona, Spain and were
con-secutively recruited over one year After completing the
collection of data for this study, patients with bronchial
colonisation were included in a randomised trial of
anti-biotic treatment the results of which have been reported
elsewhere [13] The protocol was approved by the
institu-tional review board and all patients gave written
informed consent
Study population
Eligible patients were adults over 40 years of age, smokers
or ex-smokers of at least 10 pack-years, with stable
COPD, defined as a post-bronchodilator forced
expira-tory volume in one second (FEV1)/forced vital capacity
(FVC) ratio of <70% A FEV1 of <60% of the predicted
value higher than 0.70 litres and a negative
bronchodila-tor test (increase in FEV1 <200 mL and <12% of baseline)
was required for inclusion in the study as was a history of
at least one documented exacerbation in the previous
year Clinical stability was defined by the attending
physi-cian on clinical grounds based on the absence of
symp-toms of exacerbation and use of any oral or systemic
antibiotics or a course of oral corticosteroids in the 6
weeks prior to inclusion
The exclusion criteria were the following: (1) previous
diagnosis of bronchial asthma, bronchiectasis
demon-strated by a chest X-ray or computed tomography (CT)
scan, or other relevant pulmonary diseases apart from
COPD; (2) chronic treatment with oral corticosteroids at
any dose; (3) formal contraindication for sputum
induc-tion or impossibility to obtain a valid sputum sample for
analysis; and (4) participation in another clinical study
concurrently or within the previous 3 months
Study procedures
At the time of inclusion in the study, the investigator
veri-fied that the patient met the eligibility criteria and details
of medical history were recorded Information regarding
comorbidities, particularly cardiovascular diseases,
dia-betes and liver or renal failure was collected A forced
spirometry was performed following criteria of the
Span-ish Society of Pneumology and Thoracic Surgery [14] and
sputum samples were obtained Patients unable to
pro-duce sputum were susceptible to reassessment for airway
colonisation at least one month after the initial investiga-tion for a maximum of three consecutive visits
Microbiological sputum study
A sputum sample was obtained and processed within 60 minutes on the day of the visit according to standard methods [13,15,16] Patients who did not produce spu-tum spontaneously underwent spuspu-tum induction In brief, patients were pretreated with an inhaled β2-agonist ten minutes before the nebulisation of isotonic saline (0.9%) with an ultrasonic nebuliser (Ultraneb2000, DeVil-biss Healthcare Inc., Somerset, PA, USA), that was fol-lowed by increasing concentrations of hypertonic saline (3%, 4% and 5%), for 7 min with each concentration After every induction, the patient attempted to obtain a spu-tum sample by coughing, and the nebulisation procedure was stopped when the sputum volume collected was 1
mL or more [17] In current smokers, sputum induction was performed after at least 6 hours of tobacco absti-nence The purulence of sputum was graded in a scale from 1 to 5 according to the colour from white -1- to greenish -5-, always by the same researcher at each cen-tre The sample was weighed and processed with a 4-fold volume of dithiothreitol (Sputasol, Oxoid Ltd., Hants, UK) and was cultured Sputum samples were serially diluted and plated on chocolate agar enriched, chocolate
agar with bacitracin, Haemophilus-selective agar, blood
agar, and McConkey agar Plates were incubated for 24-48 hours at 37°C and in 5% CO2 atmosphere Microorgan-isms were identified by colony morphology, Gram stain-ing and specific culture conditions (e.g., requirements for factors for growth, presence of oxidase and catalase, por-phyrin synthesis) Cultures were considered positive for bronchial colonisation if microorganisms considered as
PPMs such as Haemophilus influenzae, Haemophilus
parainfluenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, enterobacteria
and/or Staphylococcus aureus were grown at loads of at
least 100 colony-forming units (CFU)/mL according to previously defined criteria [18,19] Colonised patients were then divided into high (>105 CFU/mL) or low (≤105
CFU/mL) bacterial load according to previous studies [4,8]
Sputum concentrations of pro-inflammatory cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), inter-leukin-8 (IL-8), and tumour necrosis factor-alpha (TNF-alpha) were measured using quantitative sandwich immunoassay techniques in processed supernatants as previously described [20]
Statistical analysis
Variables were presented as mean values and standard deviations, those not following a normal distribution were presented as median and interquartile range (IQR,
Trang 325th-75th percentile) Categorical variables were
com-pared with the chi-square test and continuous variables
with the Student's t test or the Mann-Whitney U test
when data departed from normality Following univariate
analysis, variables were included in two stepwise logistic
regression models constructed as exploratory analysis to
identify independent risk factors for bronchial
colonisa-tion and factors significantly associated with high
bacte-rial load as opposed to low bactebacte-rial load and sterile
sputum cultures The variables included in the models
were: age, gender, active versus ex-smoker, pack-years of
smoking, FEV1 (% predicted), degree of dyspnoea, colour
of sputum, cardiovascular comorbidity and number of
exacerbations and hospitalisations the previous year
Bilateral two-tailed hypotheses were formulated and 95%
confidence intervals (CI) were calculated Statistical
sig-nificance was set at P < 0.05.
Results
A total of 119 patients (92.5% men) with a mean
(stan-dard deviation, SD) age of 68.1 (9.1) years were studied
The clinical characteristics of these patients are reported
in Table 1 Induction of sputum was necessary to obtain a
valid sputum sample in only 5 cases (3 in one centre and 2
in the other) Bacterial colonisation was demonstrated in
58 (48.7%) patients, 2 in samples obtained by sputum
induction Results of sputum microbiology are shown in
Table 2 Colonisation by a single PPM was recorded in 50
patients Eight subjects yielded more than one PPM in their sputum Haemophilus influenzae and H parainflu- enzae made up 72% of all bacterial isolates.
There were significant differences in cigarette con-sumption, cough, dyspnoea, comorbidities, COPD exac-erbations and hospitalisations in the previous year, and sputum colour between patients with and without bacte-rial colonisation (Table 3)
The distribution of colonised patients according to spu-tum colour is presented in Figure 1 Samples with colour
1 (white) were predominantly sterile, whereas in the sam-ples with colours 3 to 5 (yellow to greenish) the preva-lence of colonisation was higher than 80% Colour number two (light yellow) was not discriminative between colonised and non-colonised
When colonised patients were divided according to bacterial load, 36 patients had a high bacterial load (>105
CFU/mL) and the remaining 22 had a low bacterial load (≤105 CFU/mL) The characteristics of colonised patients with a high bacterial load (n = 36) were compared with a group formed by non-colonised patients (n = 61) and those with a low bacterial load (n = 22) considered together (n = 83) Statistically significant differences between the two groups in smoking (pack-years), cough, grade of dyspnoea, hospitalisations in the previous year and sputum colour persisted when patients with high bacterial loads were compared with the remaining
Table 1: Clinical characteristics of the study population
Sex, men, no (%) 112 (92.5)
Age, years, mean (SD) 68.1 (9.1)
Current smokers, no (%) 11 (9.2)
Smoking, pack-years,
mean (SD)
40 (21.1)
Cardiovascular morbidity,
no (%)
36 (29.7)
Exacerbations in the previous
year, mean (SD)
1.3 (0.5)
Requiring hospital
admission
0.3 (0.5)
Post-bronchodilator
spirometry, mean (SD)
Table 2: Potentially Pathogenic Microorganisms (PPMs) isolated in colonised COPD patients.
No (%)
Microorganisms isolated
Haemophilus parainfluenzae
15 (30)
Pseudomonas aeruginosa
5 (10)
Streptococcus pneumoniae
4 (8)
Mixed colonisations (from the above microorganisms)
H influenzae + S
pneumoniae
1
H influenzae + P
aeruginosa
3
H influenzae + H
parainfluenzae
2
P aeruginosa + S
viridans
2
Trang 4Table 3: Differences between stable COPD patients with and without bacterial colonisation
Symptoms, no (%)
Exacerbations in the previous year, no (%)
Lung function tests, mean (SD)
Sputum analysis
Pro-inflammatory cytokines, median
(IQR) in pg/mL
FVC = forced vital capacity; FEV1 = forced expiratory volume in the first second; IQR = interquartile range; IL= interleukin; TNF = tumour necrosis factor.
patients (Table 4) Sufficient sputum for inflammatory
analysis was available from only 61 subjects, all from
spontaneous sputum Sputum concentrations of
inflam-matory markers showed a great inter-individual
variabil-ity and did not follow a normal distribution There were
no significant differences in sputum concentrations for
any of the inflammatory markers analysed between
patients with or without bacterial colonisation (Table 3) The lack of significance persisted when patients with high bacterial load were compared with those with low bacte-rial load and not colonised However, in this last compar-ison, patients with high bacterial load presented consistently (but not significantly) higher concentrations
of all pro-inflammatory cytokines except IL-6 (Table 4)
Trang 5The results of the multivariate analysis were very
simi-lar when identifying the factors significantly associated
with the presence of PPMs or on classifying the
popula-tion according to bacterial load In both cases, only the
degree of dyspnoea and sputum colour were significantly
and independently associated with the presence of PPMs
and with high bacterial load Sputum colour was a
stron-ger indicator of the presence of positive cultures for
PPMs than its load (Table 5)
Discussion
In the present study, bacterial colonisation of the airways
by PPMs, mainly H influenzae and H parainfluenzae,
was reported in 49% of patients with stable COPD This
finding adds evidence to a high prevalence of bacterial
colonisation of airways in stable COPD reported by
oth-ers [4,5,9-12] Interestingly, our results using sputum
samples are quite similar to those obtained in other
stud-ies with the use of the PSB technique or bronchial lavage
for microbiologic assessment of the lower airways in
COPD [4,5,11,12,20,21] The possibility of sputum
collec-tion along a maximum of three monthly clinical visits and
the use of the induced sputum technique in selected cases
may have accounted for this high diagnostic yield of the
sputum However, most of our patients were able to
pro-duce a valid sputum sample for microbiological
examina-tion and inducexamina-tion of sputum was necessary in only 5
cases A previous study by our group demonstrated that
spontaneous and induced sputum yielded equivalent
results in terms of frequency of bacterial colonisation and
species recovered [22] A pooled analysis of data from
studies that used PSB demonstrated that a PPM load ≥102
CFU/mL should be considered abnormal and allowed the
estimation that at least one quarter of the patients with
stable COPD were colonised by PPMs [5] Furthermore,
most patients with exacerbated COPD had concentration
of PPMs > 105 [4,5] Since there is no universally accepted cut-off for high bacterial load in sputum samples, a 105
CFU/mL concentration was used in our study [4,8] With this value, 30% of our total population and almost two thirds of the colonised patients in our study had a high PPM load
Bacterial colonisation in our study was related to cumu-lative consumption of cigarette smoking, history of exac-erbations in the previous year and sputum colour Exacerbations in the previous year leading to hospitalisa-tion were associated with increased bacterial load, although this relationship disappeared on multivariate analysis In other studies, current smoking and severe air-flow obstruction have been identified as predisposing factors for bacterial colonisation in stable COPD [11,12] However, we did not observe significant differences in lung function between colonised and non-colonised patients The relationship between lung function and fre-quency of colonisation is not clear, since a lack of associa-tion between FEV1 and colonisation has also been observed in other studies [8,12,21,23] and may be due, at least in part, to the under-representation of mild patients
in most series as well as in the current study Interest-ingly, the only two factors identified in multivariate analy-sis to be significantly and independently associated with both presence of bacterial colonisation and high bacterial load were a more severe degree of dyspnoea and a darker colour of sputum The degree of dyspnoea is a marker of severity of COPD and being a categorical variable with a wider distribution in our population probably contrib-uted to its demonstrated association with colonisation, in contrast to the severity of FEV1 impairment
Regarding bronchial inflammation, it should be noted that we did not find increased sputum concentrations of pro-inflammatory cytokines in patients with bacterial colonisation Different reasons may explain this finding, including a small number of patients with valid samples for analysis, the inter-individual variability in the sputum concentrations of the cytokines was very large [24], and there was a large number of patients with low bacterial
loads In fact, Hill et al [8] have demonstrated that
mark-ers of inflammation increased progressively with increas-ing bacterial load in patients with stable COPD Consequently, when our colonised patients were catego-rized according to high or low bacterial load, besides the persistence of the clinical differences already observed between the colonised and non-colonised groups (i.e., cigarette smoking, hospitalisations in the previous year, grade of dyspnoea and sputum colour) a non-significant trend towards higher sputum concentrations of inflam-matory markers (except IL-6) was observed in patients with high bacterial load Our results concur with previ-ous observations regarding the lack of association
Figure 1 Percentage of bacterial colonisation according to
spu-tum colour (differences statistically significant at P < 0.001).
colour 1= white; 2= light yellow; 3= dark yellow; 4= light green; 5= greenish
Trang 6Table 4: Differences between colonised and non-colonised COPD patients according to bacterial load
(n = 36)
Low bacterial load (<10 5 ) and not colonised (n = 83)
P value
Smoking, pack-years,
mean (SD)
Cardiovascular morbidity,
no (%)
Comorbid conditions,
mean (SD)
Symptoms, no (%)
Exacerbations in the
previous year, no (%)
Requiring hospital
admission
0.003
Lung function tests, mean
(SD)
Sputum analysis
Pro-inflammatory
cytokines, median (IQR)
in pg/mL
FVC = forced vital capacity; FEV1 = forced expiratory volume in the first second; IQR = interquartile range; IL= interleukin; TNF = tumour necrosis factor.
Trang 7between colonisation and increased IL-6 [9,10] but are
discordant with other works showing significantly
increased bronchial IL-8 and TNF-alpha in colonised
patients, particularly with H.influenzae [9,10,21,23,25].
Therefore, our data, if confirmed in a larger sample of
patients, would also suggest a dose-response relationship
between bacterial load and bronchial inflammation and
that a threshold of bacterial load might be necessary to
elicit a significant inflammatory reaction in the airways
[5,6,26] In contrast, Sehti et al [27] examined whether
the increase in bacterial concentrations functions as a
separate mechanism of exacerbation induction,
indepen-dent of a new strain acquisition In a prospective
longitu-dinal cohort of COPD patients assessed during
exacerbations and stable disease, sputum concentrations
of pre-existing strains of H influenzae and H
haemolyti-cus were not significantly different in exacerbation versus
stable disease Concentrations of M catarrhalis and S.
pneumoniae were even lower during exacerbations
com-pared with stable periods However, concentrations of
new strains of H influenzae and M catarrhalis were
increased during exacerbations, but the differences were
small These authors speculate that change in bacterial
load was unlikely to be a major primary mechanism of
exacerbation induction in COPD [27,28] This hypothesis
is a matter of debate, because the interpretation of what a
significant increase in bacterial load is when measured in
a logarithmic scale is not clear [10], and when
trans-formed to a non-logarithmic scale, the differences in
absolute bacterial counts were of a very high magnitude
[29]
The identification of bronchial colonisation has clinical
implications Patel et al [9] demonstrated that the
pres-ence of lower airway bacterial colonisation in stable
COPD was significantly related to exacerbation
fre-quency and severity In the study of Rosell et al [5], again
high bacterial loads were associated with exacerbation
and showed a statistically significant dose-response
rela-tionship between bacterial load and exacerbation after
adjustment for covariates In our study colonised patients
had significantly more exacerbations and hospital
admis-sions the year previous to the study compared with non-colonised patients, but the significance disappeared on multivariate analysis It should be taken into account that our study was neither designed nor powered to demon-strate differences in exacerbation or hospitalisation rates between colonised and non-colonised COPD patients Therefore, the identification of patients colonised by PPMs using a non-invasive and relatively inexpensive technique such as the analysis of sputum may play an important role in the management of severe and very severe COPD, particularly if intervention studies with antibiotics demonstrate improved clinical outcomes [13]
To facilitate the diagnosis of bronchial colonisation the use of a surrogate marker could be of interest Purulence (colour) of sputum graded by the investigator with a sim-ple scale from 1 to 5 revealed significant differences in colour between colonised and non-colonised patients Patients with colour 3 or higher (dark yellow to green sputum) had a prevalence of bacterial colonisation greater than 80% The relevance of sputum colour has been already described and validated for exacerbated patients in which yellowish or greenish sputum is signifi-cantly associated with a bacterial exacerbation compared with white (non-bacterial) sputum [30,31] but the rela-tionship between sputum colour and bacterial colonisa-tion in stable COPD has deserved little attencolonisa-tion [8] The present results should be interpreted taking into account some limitations of the study, particularly the small sample size may not have allowed determination of sputum concentrations of inflammatory markers in all samples, in most cases due to the small recovery of spu-tum that did not provide enough supernatant for the quantification of inflammatory mediators The cross-sec-tional design did not allow the dynamics and time course
of bacterial colonisation and airway inflammation during exacerbations to be examined Patients with negative bronchodilator test were included to exclude individuals with asthma who are less likely to be colonised, but the results may not be extrapolated to partially reversible COPD patients High concentrations of PPMs in sputum samples, however, is a simple parameter that may help to
Table 5: Results of multivariate analysis of factors associated with presence of bacteria in sputum and with high bacterial load.
Factors associated with bacteria in sputum
Factors associated with high bacterial load as opposed to no bacteria and low bacterial load
Trang 8select candidates to participate in antibiotic trials of
sta-ble COPD in order to demonstrate bacterial eradication
and potentially prolong time to exacerbation [6,32,33]
Conclusions
Almost half of a population of ambulatory moderate to
very severe COPD patients carry PPMs in their airways
Colonised patients had more severe dyspnoea, and
spu-tum colour allows the identification of patients most
likely to be colonised by PPMs
List of abbreviations
CFU: colony-forming units; CI: confidence interval;
COPD: Chronic obstructive pulmonary disease; CT:
computed tomography; FEV1: forced expiratory volume
in one second; FVC: forced vital capacity; IQR:
inter-quartile range; 1: interleukin-1; 6: interleukin-6;
IL-8: interleukin-8; OR: odds ratio; PPMs: potentially
patho-genic microorganisms; PSB: protected specimen brush;
SD: standard deviation; TNF-alpha: tumour necrosis
fac-tor-alpha
Competing interests
Marc Miravitlles has received honoraria for consultancy and speaking at
scien-tific meetings from Bayer Schering, GlaxoSmithKline, Boehringer Ingelheim
and AstraZeneca Cristian de la Roza is fully employed in the Medical
Depart-ment of Bayer Schering Pharma Antoni Torres has received honoraria for
con-sultancy and speaking at scientific meetings from Bayer and Covidien Alicia
Marín, Eduard Monsó, Sara Vilà, Ramona Hervás, Cristina Esquinas, Marian
García, Laura Millares and Josep Morera have no conflict of interest to disclose.
Authors' contributions
MM designed the study, participated in the analysis and interpretation of data
and wrote the manuscript EM, JM and AT designed the study, and participated
in the analysis and interpretation of data AM and SV recruited the patients,
col-lected data and participate in the design and analysis CR participated in the
design and analysis of the study CE and RH collected and processed the
sam-ples, and created and cleaned the database LM and MG perfomed the
micro-biological investigations All authors read and approved the final manuscript.
Acknowledgements
This study was funded by unrestricted grants from Fundación Respira-SEPAR
and La Marató de TV3 and Bayer Schering Pharma We thank Marta Pulido, MD,
for providing an outline for this manuscript and support in editing and journal
styling Bayer Schering Pharma was the source of funding for medical writing
The funding bodies had no role in study design, data analysis, interpretation
and writing of the manuscript, and in the decision to submit the manuscript
for publication.
Author Details
1 Fundació Clínic Institut D'Investigacions Biomèdiques August Pi i Sunyer
(IDIBAPS) Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain,
2 Department of Pneumology, Hospital Germans Trias i Pujol Autonomous
University of Barcelona; Ciber de Enfermedades Respiratorias (CIBERES),
Barcelona, Spain, 3 Department of Pneumology, Hospital Germans Trias i Pujol,
Ciber de Enfermedades Respiratorias (CIBERES), Badalona, Barcelona, Spain,
4 Medical Department, Bayer Schering Pharma, Sant Joan Despi, Barcelona,
Spain and 5 Department of Pneumology, Institut Clínic del Tòrax (IDIBAPS),
Hospital Clínic, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona,
Spain
References
1 Miravitlles M, Murio C, Guerrero T, Gisbert R: Pharmacoeconomic
evaluation of acute exacerbations of chronic bronchitis and COPD
Chest 2002, 121:1449-1455.
2 Donaldson GC, Seemungal TA, Bhowmik A, Wedzicha JA: Relationship between exacerbation frequency and lung function decline in chronic
obstructive pulmonary disease Thorax 2002, 57:847-852.
3 Soler-Cataluña JJ, Martínez-García MA, Román P Sánchez, Salcedo E, Navarro M, Ochando R: Severe acute exacerbations and mortality in
patients with chronic obstructive pulmonary disease Thorax 2005,
60:925-931.
4 Monsó E, Ruiz J, Rosell A, Manterola J, Fiz J, Morera J, Ausina V: Bacterial infection in chronic obstructive pulmonary disease A study of stable
and exacerbated outpatients using the protected specimen brush Am
J Respir Crit Care Med 1995, 152:1316-1320.
5 Rosell A, Monsó E, Soler N, Torres F, Angrill J, Riise G, Zalacaín R, Morera J, Torres A: Microbiologic determinants of exacerbation in chronic
obstructive pulmonary disease Arch Intern Med 2005, 165:891-897.
6 Miravitlles M: Exacerbations of chronic obstructive pulmonary disease:
when are bacteria important? Eur Respir J 2002, 20(Suppl 36):1s-11s.
7 Papi A, Bellettato CM, Braccioni F, Romagnoli M, Casolari P, Caramori G, Fabbri LM, Johnston SL: Infections and airway inflammation in chronic
obstructive pulmonary disease severe exacerbations Am J Respir Crit
Care Med 2006, 173:1114-1121.
8 Hill AT, Campbell EJ, Hill SL, Bayley DL, Stockley RA: Association between airway bacterial load and markers of airway inflammation in patients
with stable chronic bronchitis Am J Med 2000, 109:288-295.
9 Patel IS, Seemungal TA, Wilks M, Lloyd-Owen SJ, Wedzicha JA:
Relationship between bacterial colonisation and the frequency,
character, and severity of COPD exacerbations Thorax 2002,
57:759-764.
10 Wilkinson TM, Patel IS, Wilks M, Donaldson GC, Wedzicha JA: Airway bacterial load and FEV1 decline in patients with chronic obstructive
pulmonary disease Am J Respir Crit Care Med 2003, 167:1090-1095.
11 Zalacain R, Sobradillo V, Amilibia J, Barrón J, Achótegui V, Pijoan JI, Llorente JL: Predisposing factors to bacterial colonisation in chronic
obstructive pulmonary disease Eur Respir J 1999, 13:343-348.
12 Monsó E, Rosell A, Bonet G, Manterola J, Cardona PJ, Ruiz J, Morera J: Risk
factors for lower airway bacterial colonisation in chronic bronchitis
Eur Respir J 1999, 13:338-342.
13 Miravitlles M, Marín A, Monsó E, Vilà S, de la Roza C, Hervás R, Esquinas C, García M, Millares L, Morera J, Torres A: Efficacy of moxifloxacin in the
treatment of bronchial colonisation in COPD Eur Respir J 2009,
34:1066-1071.
14 Sanchis J y Grupo de trabajo de la SEPAR: Normativa para la práctica de
la espirometría forzada Arch Bronconeumol 1989, 25:132-142.
15 Pin I, Gibson PG, Kolendowicz R, Girgis-Gabardo A, Denburg JA, Hargreave
FE, Dolovich J: Use induced sputum cell counts to investigate airway
inflammation in asthma Thorax 1992, 47:25-29.
16 Pizzichini E, Pizzichini MM, Efthimiadis A, Evans S, Morris MM, Squillace D, Gleich GJ, Dolovich J, Hargreave FE: Indices of airway inflammation in induced sputum: reproducibility and validity of cell and fluid-phase
measurements Am J Respir Crit Care Med 1996, 154:308-317.
17 Aaron SD, Angel JB, Lunau M, Wright K, Fex C, Le Saux N, Dales RE: Granulocyte inflammatory markers and airway infection during acute
exacerbation of chronic obstructive pulmonary disease Am J Respir Crit
Care Med 2001, 163:349-355.
18 Angrill J, Agustí C, de Celis R, Rañó A, Gonzalez J, Solé T, Xaubet A, Rodriguez-Roisin R, Torres A: Bacterial colonisation in patients with
bronchiectasis: microbiological pattern and risk factors Thorax 2002,
57:15-19.
19 Cabello H, Torres A, Celis R, El-Ebiary M, Puig de la Bellacasa J, Xaubet A, González J, Agustí C, Soler N: Bacterial colonisation of distal airways in
healthy subjects and chronic lung disease: a bronchoscopic study Eur
Respir J 1997, 10:1137-1144.
20 Weinreich UM, Korsgaard J: Bacterial colonisation of lower airways in
health and chronic lung disease Clinical Respiratory Journal 2008,
2:116-122.
21 Soler N, Ewig S, Torres A, Filella X, Gonzalez J, Xaubet A: Airway inflammation and bronchial microbial patterns in patients with stable
chronic obstructive pulmonary disease Eur Respir J 1999, 14:1015-1022.
Received: 8 January 2010 Accepted: 14 May 2010
Published: 14 May 2010
This article is available from: http://respiratory-research.com/content/11/1/58
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Respiratory Research 2010, 11:58
Trang 922 Marin A, García M, Badorrey I, Sabrià M, Morera J, Monsó E: Spontaneous
sputum production as a marker of bacterial colonisation in stable
COPD Eur Respir J 2005, 26(Suppl 49):232 abstract
23 Sethi S, Maloney J, Grove L, Wrona C, Berenson CS: Airway inflammation
and bronchial bacterial colonisation in chronic obstructive pulmonary
disease Am J Respir Crit Care Med 2006, 173:991-998.
24 Sapey E, Bayley D, Ahmad A, Newbold P, Snell N, Stockley RA:
Inter-relationships between inflammatory markers in patients with stable
COPD with bronchitis: intra-patient and inter-patient variability
Thorax 2008, 63:493-503.
25 Bresser P, Out TA, van Alphen L, Jansen HM, Lutter R: Airway
inflammation in nonobstructive and obstructive chronic bronchitis
with chronic Haemophilus influenzae airway infection Comparison
with noninfected patients with chronic obstructive pulmonary
disease Am J Respir Crit Care Med 2000, 162:947-952.
26 Bresser P, van Alphen L, Habets FJ, Hart AA, Dankert J, Jansen HM, Lutter R:
Persisting Haemophilus influenzae strains induce lower levels of
interleukin-6 and interleukin-8 in H292 lung epithelial cells than
nonpersisting strains Eur Respir J 1997, 10:2319-2326.
27 Sethi S, Sethi R, Eschberger K, Lobbins P, Cai X, Grant BJ, Murphy TF:
Airway bacterial concentration and exacerbations of chronic
obstructive pulmonary disease Am J Respir Crit Care Med 2007,
176:356-361.
28 Sethi S, Evans N, Grant BJ, Murphy TF: New strains of bacteria and
exacerbations of chronic obstructive pulmonary disease N Engl J Med
2002, 347:465-471.
29 Abusriwil H, Stockley RA: Bacterial load and exacerbations of COPD Am
J Respir Crit Care Med 2008, 177:1048-1049.
30 Stockley RA, O'Brien C, Pye A, Hill SL: Relationship of sputum colour to
nature and outpatient management of acute exacerbations of COPD
Chest 2000, 117:1638-1645.
31 Soler N, Agustí C, Angrill J, Puig de la Bellacasa J, Torres A: Bronchoscopic
validation of the significance of sputum purulence in severe
exacerbations of chronic obstructive pulmonary disease Thorax 2006,
62:29-35.
32 Wilson R: Using antibiotics to delay exacerbations of chronic
obstructive pulmonary disease Hot Topics Respir Dis 2006, 2:21-26.
33 Chodosh S: Clinical significance of the infection-free interval in the
management of acute bacterial exacerbations of chronic bronchitis
Chest 2005, 127:2231-226.
doi: 10.1186/1465-9921-11-58
Cite this article as: Miravitlles et al., Colour of sputum is a marker for
bacte-rial colonisation in chronic obstructive pulmonary disease Respiratory
Research 2010, 11:58